How The Detroit Tigers Are Roaring Into The Playoffs
With an 0.2% chance to make the playoffs after 118 games, the Tigers are defying the odds.
On August 10th, the Detroit Tigers season looked to be all but over. Sitting in 4th-place in the AL Central with a 55-63 record - the 24th best in the 30-team MLB - the Tigers held a 0.2% chance to make the playoffs per FanGraphs. Fast-forward just about seven weeks and Detroit is on the precipice of the post-season.
How the $#@! did they manage to pull this off!?! The answer - a little bit of skill, a dash of regression to the mean, and a touch of luck.
Batted Ball Variance
In my last article, which discussed the drastic turnaround for Nick Castellanos this season, I discussed the statistical phenomenon of batting average on balls in play (a.k.a., BABIP). BABIP is a highly variable statistic based on quality of the opposing defense, field conditions, and just plain random luck. Batters and pitchers - especially pitchers - have little control over what happens once the ball is put in the field of play, so sometimes high quality contact can result in an out, while low quality contact results in a hit. Over the long run this will even out, but it takes a fairly large sample size of balls in play to do so.1 For teams, this means regression towards the league average. Teams with relatively high BABIP can be expected to see negative regression towards the MLB average, and vice-versa. The Tigers had an offensive BABIP of 0.278 on August 10th, 0.012 points below the league average of 0.290. This tied the Seattle Mariners for 4th-lowest BABIP compared to the MLB average during that timespan. Since then, regression hit. The Tigers have had a BABIP of 0.318 since August 11th, good for the second-best BABIP vs. League Average (+0.026).2 The random variance in Pitching BABIP is even more extreme. While skilled batters can to some extent control where they hit the ball relative to fielders, and how difficult the batted ball is to field, pitchers have far less control.3 When a ball is in play, pitchers are merely at the mercy of their defense. While some pitchers are better or worse at promoting soft contact and ground balls, ultimately random variance and defensive ability play an outsized role. While Tigers pitchers threw to a perfectly league-average BABIP through August 10th, they have benefited greatly from some batted ball variance since. From August 11th to now, the Tigers hold the 3rd-lowest Pitcher BABIP vs. League Average (-0.038), as their pitching staff mustered a BABIP if 0.252 against the MLB average 0.290. So while the Tigers offense has been balancing out their bad luck from the first part of the season, their pitchers have benefited from a bit of good luck themselves of late.4
Luck
Famed baseball statistician Bill James created the Pythagorean theorem of baseball. This relates the number of runs a team has scored and allowed to its actual winning percentage, based on the belief that runs scored compared to runs allowed is a better indicator of a team's future performance than a team's actual winning percentage.5 This is another aspect of baseball in which luck can be observed. The Pythagorean formula is highly accurate and will almost always accurately predict a teams’ record based on runs scored versus allowed. One-run games can tend to be fairly 50-50 win-to-loss for all teams, regardless of how good a team is, over the long run. Sometimes teams deviate from this expectation for short periods. Most always, teams will regress to the Pythagorean expectation as this deviation is largely due to luck, which is nearly impossible to reproduce or maintain. The difference between a teams actual wins and Pythagorean wins is aptly termed “Luck”. The graph below shows how, over time, a team’s Luck tends to stabilize by plotting the cumulative average standard deviation in Luck across the league over a 20-year period.
The Tigers had an actual record of 55-63 on August 10th, but a Pythagorean record of 57-61. Since then, they are +1 in Luck, with 28 wins against 27 expected wins. This is admittedly a small shift, however the Tigers have largely benefitted from Luck by way of their opponents. Kansas City and Seattle, two teams fighting with Detroit for the last playoff spot, each have Pythagorean records expecting 4-more wins than they’ve actually had. With the race this close so late in the season, these 4 wins make a world of difference.
A Little Bit of Skill
The Tigers did just get lucky, a little skill went into their playoff push too. The Tigers have been making much higher quality contact of late. On August 10th, the Tigers held a Barrel% of 7.4%.6 Since, that rate has been 8.0%. Their pitching staff has been incredible too. The team’s ERA on August 10th was ranked 14th in the MLB at 3.98. In the six-plus weeks since, the Tigers have thrown a league-best 2.67, nearly 3-tenths of a point above the second place Atlanta Braves’ 2.97 ERA!
The Tigers have been lucky, but they’ve also been playing fantastic baseball.
Down the Stretch
The Tigers have played themselves back into the race, and benefitted from a little bit of good luck. While it should be close down to the wire, the Tiger’s miraculous turnaround has put them on the precipice of the playoffs and made them a fan-favorite across the MLB.
Oh, one last bit of good luck, the team just so happens to end the season against the historically awful Chicago White Sox. Its a great time to be a Tigers fan.
The Phillies had the highest BABIP vs MLB average at +0.029. The MLB average BABIP during that time span is 0.291
Stats via FanGraphs
Statcast defines a “Barrel” as a well-struck ball where the combination of exit velocity and launch angle generally leads to a minimum .500 batting average and 1.500 slugging percentage. Per MLB.com, a batted ball is “barreled” when it has an exit velocity of at least 98 mph. At that speed, balls with a launch angle between 26-30 degrees always attain “barreled” classification. For every mph over 98 degrees, the range of launch angle expands.